KVM: nVMX: Use '-1' in 'hv_evmcs_vmptr' to indicate that eVMCS is not in use

Instead of checking 'vmx->nested.hv_evmcs' use '-1' in
'vmx->nested.hv_evmcs_vmptr' to indicate 'evmcs is not in use' state. This
matches how we check 'vmx->nested.current_vmptr'. Introduce EVMPTR_INVALID
and evmptr_is_valid() and use it instead of raw '-1' check as a preparation
to adding other 'special' values.

No functional change intended.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210526132026.270394-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/evmcs.c

@@ -319,6 +319,9 @@ bool nested_enlightened_vmentry(struct kvm_vcpu *vcpu, u64 *evmcs_gpa)
 	if (unlikely(!assist_page.enlighten_vmentry))
 		return false;
 
+	if (unlikely(!evmptr_is_valid(assist_page.current_nested_vmcs)))
+		return false;
+
 	*evmcs_gpa = assist_page.current_nested_vmcs;
 
 	return true;

arch/x86/kvm/vmx/evmcs.h

@@ -197,6 +197,13 @@ static inline void evmcs_load(u64 phys_addr) {}
 static inline void evmcs_touch_msr_bitmap(void) {}
 #endif /* IS_ENABLED(CONFIG_HYPERV) */
 
+#define EVMPTR_INVALID (-1ULL)
+
+static inline bool evmptr_is_valid(u64 evmptr)
+{
+	return evmptr != EVMPTR_INVALID;
+}
+
 enum nested_evmptrld_status {
 	EVMPTRLD_DISABLED,
 	EVMPTRLD_SUCCEEDED,

arch/x86/kvm/vmx/nested.c

@@ -187,7 +187,8 @@ static int nested_vmx_fail(struct kvm_vcpu *vcpu, u32 vm_instruction_error)
 	 * failValid writes the error number to the current VMCS, which
 	 * can't be done if there isn't a current VMCS.
 	 */
-	if (vmx->nested.current_vmptr == -1ull && !vmx->nested.hv_evmcs)
+	if (vmx->nested.current_vmptr == -1ull &&
+	    !evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 		return nested_vmx_failInvalid(vcpu);
 
 	return nested_vmx_failValid(vcpu, vm_instruction_error);
@@ -221,12 +222,12 @@ static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 
-	if (!vmx->nested.hv_evmcs)
-		return;
-
+	if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
 		kvm_vcpu_unmap(vcpu, &vmx->nested.hv_evmcs_map, true);
-	vmx->nested.hv_evmcs_vmptr = 0;
 		vmx->nested.hv_evmcs = NULL;
+	}
+
+	vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;
 }
 
 static void vmx_sync_vmcs_host_state(struct vcpu_vmx *vmx,
@@ -1981,9 +1982,7 @@ static enum nested_evmptrld_status nested_vmx_handle_enlightened_vmptrld(
 	if (!nested_enlightened_vmentry(vcpu, &evmcs_gpa))
 		return EVMPTRLD_DISABLED;
 
-	if (unlikely(!vmx->nested.hv_evmcs ||
-		     evmcs_gpa != vmx->nested.hv_evmcs_vmptr)) {
-		if (!vmx->nested.hv_evmcs)
+	if (unlikely(evmcs_gpa != vmx->nested.hv_evmcs_vmptr)) {
 		vmx->nested.current_vmptr = -1ull;
 
 		nested_release_evmcs(vcpu);
@@ -2055,7 +2054,7 @@ void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 
-	if (vmx->nested.hv_evmcs) {
+	if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
 		copy_vmcs12_to_enlightened(vmx);
 		/* All fields are clean */
 		vmx->nested.hv_evmcs->hv_clean_fields |=
@@ -2207,7 +2206,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	u32 exec_control;
 	u64 guest_efer = nested_vmx_calc_efer(vmx, vmcs12);
 
-	if (vmx->nested.dirty_vmcs12 || vmx->nested.hv_evmcs)
+	if (vmx->nested.dirty_vmcs12 || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 		prepare_vmcs02_early_rare(vmx, vmcs12);
 
 	/*
@@ -2492,15 +2491,14 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 			  enum vm_entry_failure_code *entry_failure_code)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	struct hv_enlightened_vmcs *hv_evmcs = vmx->nested.hv_evmcs;
 	bool load_guest_pdptrs_vmcs12 = false;
 
-	if (vmx->nested.dirty_vmcs12 || hv_evmcs) {
+	if (vmx->nested.dirty_vmcs12 || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
 		prepare_vmcs02_rare(vmx, vmcs12);
 		vmx->nested.dirty_vmcs12 = false;
 
-		load_guest_pdptrs_vmcs12 = !hv_evmcs ||
-			!(hv_evmcs->hv_clean_fields &
+		load_guest_pdptrs_vmcs12 = !evmptr_is_valid(vmx->nested.hv_evmcs_vmptr) ||
+			!(vmx->nested.hv_evmcs->hv_clean_fields &
 			  HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP1);
 	}
 
@@ -3102,7 +3100,8 @@ static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu)
 	 * L2 was running), map it here to make sure vmcs12 changes are
 	 * properly reflected.
 	 */
-	if (vmx->nested.enlightened_vmcs_enabled && !vmx->nested.hv_evmcs) {
+	if (vmx->nested.enlightened_vmcs_enabled &&
+	    !evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
 		enum nested_evmptrld_status evmptrld_status =
 			nested_vmx_handle_enlightened_vmptrld(vcpu, false);
 
@@ -3465,7 +3464,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
 
 	load_vmcs12_host_state(vcpu, vmcs12);
 	vmcs12->vm_exit_reason = exit_reason.full;
-	if (enable_shadow_vmcs || vmx->nested.hv_evmcs)
+	if (enable_shadow_vmcs || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 		vmx->nested.need_vmcs12_to_shadow_sync = true;
 	return NVMX_VMENTRY_VMEXIT;
 }
@@ -3493,7 +3492,8 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 		return nested_vmx_failInvalid(vcpu);
 	}
 
-	if (CC(!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull))
+	if (CC(!evmptr_is_valid(vmx->nested.hv_evmcs_vmptr) &&
+	       vmx->nested.current_vmptr == -1ull))
 		return nested_vmx_failInvalid(vcpu);
 
 	vmcs12 = get_vmcs12(vcpu);
@@ -3507,7 +3507,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	if (CC(vmcs12->hdr.shadow_vmcs))
 		return nested_vmx_failInvalid(vcpu);
 
-	if (vmx->nested.hv_evmcs) {
+	if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
 		copy_enlightened_to_vmcs12(vmx);
 		/* Enlightened VMCS doesn't have launch state */
 		vmcs12->launch_state = !launch;
@@ -4066,10 +4066,11 @@ static void sync_vmcs02_to_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 
-	if (vmx->nested.hv_evmcs)
+	if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 		sync_vmcs02_to_vmcs12_rare(vcpu, vmcs12);
 
-	vmx->nested.need_sync_vmcs02_to_vmcs12_rare = !vmx->nested.hv_evmcs;
+	vmx->nested.need_sync_vmcs02_to_vmcs12_rare =
+		!evmptr_is_valid(vmx->nested.hv_evmcs_vmptr);
 
 	vmcs12->guest_cr0 = vmcs12_guest_cr0(vcpu, vmcs12);
 	vmcs12->guest_cr4 = vmcs12_guest_cr4(vcpu, vmcs12);
@@ -4569,7 +4570,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
 	}
 
 	if ((vm_exit_reason != -1) &&
-	    (enable_shadow_vmcs || vmx->nested.hv_evmcs))
+	    (enable_shadow_vmcs || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)))
 		vmx->nested.need_vmcs12_to_shadow_sync = true;
 
 	/* in case we halted in L2 */
@@ -5265,7 +5266,7 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 		return nested_vmx_fail(vcpu, VMXERR_VMPTRLD_VMXON_POINTER);
 
 	/* Forbid normal VMPTRLD if Enlightened version was used */
-	if (vmx->nested.hv_evmcs)
+	if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 		return 1;
 
 	if (vmx->nested.current_vmptr != vmptr) {
@@ -5321,7 +5322,7 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu)
 	if (!nested_vmx_check_permission(vcpu))
 		return 1;
 
-	if (unlikely(to_vmx(vcpu)->nested.hv_evmcs))
+	if (unlikely(evmptr_is_valid(to_vmx(vcpu)->nested.hv_evmcs_vmptr)))
 		return 1;
 
 	if (get_vmx_mem_address(vcpu, exit_qual, instr_info,
@@ -6093,7 +6094,7 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
 		if (vmx_has_valid_vmcs12(vcpu)) {
 			kvm_state.size += sizeof(user_vmx_nested_state->vmcs12);
 
-			if (vmx->nested.hv_evmcs)
+			if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 				kvm_state.flags |= KVM_STATE_NESTED_EVMCS;
 
 			if (is_guest_mode(vcpu) &&
@@ -6149,7 +6150,7 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
 	} else  {
 		copy_vmcs02_to_vmcs12_rare(vcpu, get_vmcs12(vcpu));
 		if (!vmx->nested.need_vmcs12_to_shadow_sync) {
-			if (vmx->nested.hv_evmcs)
+			if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
 				copy_enlightened_to_vmcs12(vmx);
 			else if (enable_shadow_vmcs)
 				copy_shadow_to_vmcs12(vmx);

arch/x86/kvm/vmx/nested.h

@@ -63,7 +63,7 @@ static inline int vmx_has_valid_vmcs12(struct kvm_vcpu *vcpu)
 	 * have vmcs12 if it is true.
 	 */
 	return is_guest_mode(vcpu) || vmx->nested.current_vmptr != -1ull ||
-		vmx->nested.hv_evmcs;
+		evmptr_is_valid(vmx->nested.hv_evmcs_vmptr);
 }
 
 static inline u16 nested_get_vpid02(struct kvm_vcpu *vcpu)

arch/x86/kvm/vmx/vmx.c

@@ -6861,6 +6861,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
 
 	vmx->nested.posted_intr_nv = -1;
 	vmx->nested.current_vmptr = -1ull;
+	vmx->nested.hv_evmcs_vmptr = EVMPTR_INVALID;
 
 	vcpu->arch.microcode_version = 0x100000000ULL;
 	vmx->msr_ia32_feature_control_valid_bits = FEAT_CTL_LOCKED;